HapiJuice

Okay, so I have solved the problem. For one of the computers, use a different port in the launch options for the game. add "-port=2350" without quotes to the launch parameters of the game and it should work. It worked for us! How to access the launch parameters for steam: Right click on your Arma 3 alpha in your games library and select properties. Under the general tab, click the "set launch options" button and enter "-port=2350" without quotes and hit okay.

jxjcsn, Yes we do have 2 individual copies of Arma 3 and we are trying to join an external multiplayer server. I just tried to play on a different server while she was on a different one and it let me in just fine. I also looked at that ticket check post before I posted and concluded that I got that error for a different reason. We are both on the stable build and we are not running any mods. I will try to have her join a local game over LAN and let you know how it turns out. I'm also thinking that the server we are trying to join is seeing that there are multiple connections coming from the same IP and rejecting them. If that was the case, why would I be getting the ticket check failed?

Okay, so my girlfriend and I live in the same house and go through the same router to play. We tried to join our first game together today and she got in and was playing and when I joined, My game crashed and in game it said something along the lines of my steam ticket check had failed. Is there a way that we can be recognized as different IPs even though we are in the same network? I have a 2wire router/modem and it sucks. I have already forwarded my ports on this computer (port 2302). I'm not quite sure what to do now to get it so we both can play on the same server. If I can change the port that the game uses, I can port forward the different ports for the computers and hopefully that would solve this. But I don't know how to change the port. If anyone knows, please let me know